1. Field of the Invention:
The present invention relates to a button sewing machine for sewing a button to a fabric through cooperation between a sewing needle reciprocatingly movable along a needle path by the rotation of the main shaft of the sewing machine and a button gripping means movable across the needle path on the bed of the sewing machine, and more particularly to a button sewing machine having a detector means for detecting the condition in which a button is properly gripped by the button gripping means.
2. Description of the Prior Art:
Button sewing machines are generally provided with a button feed device for automatically feeding buttons one by one to the sewing point on the sewing machine. For example, button feed devices disclosed in U.S. Pat. Nos. 2,830,549 and 3,382,824 have a chute extending obliquely from a button supply hopper to the sewing point for guiding a row of buttons slidably therealong. The buttons are successively stitched to a fabric as the sewing needle is moved up and down at the sewing point.
When the button supply hopper runs short of buttons or the chute is jammed with buttons, so that no button can be supplied any longer, or when a button fed to the sewing point is not properly held in position and hence cannot be clamped, button-free stitches with no button sewn thereby are formed on the fabric as the sewing operation progresses. With the conventional button sewing machines, therefore, the operator is always required to pay attention to the manner in which the buttons are fed. As a result, the button sewing operation cannot be automatized or still needs an expenditure of manual labor.